Dendrimer為高分枝狀巨分子結構，其表面具有高數量帶有官能基的枝鏈端，依合成方式可產生不同官能基，常被應用在生醫及材料上；奈米碳管因其優異的機械強度、導電特性與電子傳送能力，常用來做電子元件上的應用，特別是感測器。本實驗主要以聚乙烯二胺樹枝狀分子(polyamidoamine (PAMAM) dendrimer)及多壁奈米碳管(multi-walled carbon nanotube, MWCNT)來製備生物感測器，並經由熱重損失儀及紅外線光譜分析此複合材料之組成及鍵結後官能基，利用11-mercaptoundecanoic acid及β-mercapto¬ethylamine修飾拋棄式金電極片之表面，利用循環伏安電儀(cyclic voltammetry)並選用K3Fe(CN)6電解液分析複合材料之電化學特性。檢測實驗分析可分為兩部分: (1)第一部分使用dendrimer (G4)/MWCNT奈米複合材料修飾在金電極(gold electrode, AuE)上，將葡萄糖氧化(GOX)以靜電吸引力的方式吸附在dendrimer(G4)/MWCNT-AuE上，作為葡萄糖感測器；(2)第二部分利用dendrimer (G4.5)與抗體(Ab2)及過氧化酵素(HRP)所形成的生物聚合物，製備三明治型(Ab1/Ag/Ab2)的過氧化氫感測器。感測器主要以電化學式，即循環伏安法(CV)與計時安培法(CA)偵測電流訊號作為感測原理。
第一部分主要討論PAMAM dendrimer (G4)在不同溶液pH環境下質子化過程對於葡萄糖感測之影響，其偵測靈敏度為0.375~37.500 μM。另外，雖然GOX在pH 4-7具最佳活性，本實驗發現當電極表面選用pH敏感性高分子時，需考慮質子之消耗會造成電化學上氧化還原反應之影響。第二部分討論巨樹枝狀分子PAMAM dendrimer (G4.5)與線性分子在感測穩定度及靈敏度上的差異，樹枝狀分子具有空間上效應(site isolation effect)，當鍵結HRP時能具有較高活性及靈敏度。

Polyamidoamine (PAMAM) dendrimers, highly branched dendritic macromolecules, were used to modify the surface of electrodes due to their good biocompatibility and adequate functional groups for the reagent fixation. Carbon nanotube-mounted biosensors have been developed for the detection because of the superior electrocatalytic performance of carbon nanotubes. A hybrid nanocomposite of multi-walled carbon nanotube (MWCNT) and polyamidoamine dendrimer (PAMAM) have been synthesized and mount on the disposable gold electrode. Compared with bare gold electrode, MWCNT/PAMAM modified electrode not only significant enhanced the redox peak current but also decreased the peak-to-peak separation in aqueous ferro-ferricyanide electrolyte, suggesting that modified electrode can remarkably improve the sensitivity of sensor.
In this work, we prepare two kind of sensors: (1) Glucose biosensor: the glucose oxidase (GOX) was further immobilized on the MWCNT/PAMAM modified electrode through the electrostatic interaction. (2) Hydrogen peroxide biosensor: the horseradish peroxidase (HRP), PAMAM dendrimer(G4.5) and interleukin-6(IL-6) antibody were synthesized as biocomposite, then modified on the disposal electrode through Antibody 1/Antigen/Antibody 2(sandwich type) interaction.
The aim of first work(glucose biosensor) is to derive the surface and diffusion control factors contributed by protons on the redox of glucose oxidase(GOX), showing how a proton involve in both pH-dependent dendrimer modified electrode and electron transfer reaction of GOX. In second work(hydrogen peroxide biosensor), because of the site isolation effect, G4.5 dendrimer-based H2O2 biosensor provides space for enzyme reaction and shows high sensitivity for detection of H2O2.

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